7-Zip is a

free and open-source Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source ...

file archiver A file archiver is a computer program that combines a number of files together into one archive file, or a series of archive files, for easier transportation or storage. File archivers may employ lossless data compression in their archive formats ...

, a utility used to place groups of files within compressed containers known as "archives". It is developed by Igor Pavlov and was first released in 1999. 7-Zip has its own archive format called 7z, but can read and write several others. The program can be used from a Windows

graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows User (computing), users to Human–computer interaction, interact with electronic devices through graphical icon (comp ...

that also features shell integration, from a Windows command-line interface as the command 7za.exe, and from

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inte ...

systems as p7zip. Most of the 7-Zip

source code In computing, source code, or simply code, is any collection of code, with or without comment (computer programming), comments, written using a human-readable programming language, usually as plain text. The source code of a Computer program, p ...

is under the LGPL-2.1-or-later license; the unRAR code, however, is under the LGPL-2.1-or-later license with an "unRAR restriction", which states that developers are not permitted to use the code to

reverse-engineer Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...

the

RAR RAR or Rar may refer to: * Radio acoustic ranging, a non-visual technique for determining a ship's position at sea * "rar", the ISO 639-2 code for the Cook Islands Māori language * RAR (file format), a proprietary compressed archive file format in ...

compression algorithm. Since version 21.01 alpha, preliminary Linux support has been added to the upstream instead of the p7zip project.

Archive formats

7z

By default, 7-Zip creates 7z-format archives with a .7z

file extension A filename extension, file name extension or file extension is a suffix to the name of a computer file (e.g., .txt, .docx, .md). The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically ...

. Each archive can contain multiple directories and files. As a ''container'' format, security or size reduction are achieved by looking for similarities throughout the data using a stacked combination of filters. These can consist of pre-processors,

compression algorithms In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

, and

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can dec ...

filters. The core 7z compression uses a variety of

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...

s, the most common of which are bzip2,

PPMd Prediction by partial matching (PPM) is an adaptive statistical data compression technique based on context modeling and prediction. PPM models use a set of previous symbols in the uncompressed symbol stream to predict the next symbol in the stre ...

, LZMA2, and LZMA. Developed by Pavlov, LZMA is a relatively new system, making its debut as part of the 7z format. LZMA uses an LZ-based sliding dictionary of up to 3840 MB in size, backed by a range coder. The native 7z

file format A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, pr ...

is open and

modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...

File name A filename or file name is a name used to uniquely identify a computer file in a directory structure. Different file systems impose different restrictions on filename lengths. A filename may (depending on the file system) include: * name &nda ...

s are stored as

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...

. In 2011,

TopTenReviews Future plc is an international multimedia company established in the United Kingdom in 1985. The company has over 220 brands that span magazines, newsletters, websites, and events in fields such as video games, technology, films, music, photogr ...

found that the 7z compression was at least 17% better than

ZIP Zip, Zips or ZIP may refer to: Common uses * ZIP Code, USPS postal code * Zipper or zip, clothing fastener Science and technology Computing * ZIP (file format), a compressed archive file format ** zip, a command-line program from Info-ZIP * Zi ...

, and 7-Zip's own site has since 2002 reported that while compression ratio results are very dependent upon the data used for the tests, "Usually, 7-Zip compresses to 7z format 30–70% better than to zip format, and 7-Zip compresses to zip format 2–10% better than most other zip-compatible programs." The 7z file format specification is distributed with the program's source code, in the "doc" sub-directory.

Others

7-Zip supports a number of other compression and non-compression archive formats (both for packing and unpacking), including

gzip gzip is a file format and a software application used for file compression and decompression. The program was created by Jean-loup Gailly and Mark Adler as a free software replacement for the compress program used in early Unix systems, and ...

, bzip2, xz,

tar Tar is a dark brown or black viscosity, viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic matter, organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. ...

, and WIM. The utility also supports unpacking

APM APM, apm, or Apm may refer to: Technology Computer technology * Active policy management, a discipline within enterprise software *Advanced Power Management, a legacy technology in personal computers * Apple Partition Map, computer disk partit ...

, ar,

ARJ ARJ (Archived by Robert Jung) is a software tool designed by Robert K. Jung for creating high-efficiency compressed file archives. ARJ is currently on version 2.86 for MS-DOS and 3.20 for Microsoft Windows and supports 16-bit, 32-bit and 64-bit ...

chm CHM may refer to: Biology and medicine * CHM, abbreviation for Clearing House Mechanism under the Convention on Biological Diversity * CHM, a human gene that encodes Rab escort protein 1 * Choroideremia, a retinal disease caused by mutations in the ...

cpio cpio is a general file archiver utility and its associated file format. It is primarily installed on Unix-like computer operating systems. The software utility was originally intended as a tape archiving program as part of the Programmer's Work ...

, deb,

FLV Flash Video is a container file format used to deliver digital video content (e.g., TV shows, movies, etc.) over the Internet using Adobe Flash Player version 6 and newer. Flash Video content may also be embedded within SWF files. There ar ...

JAR A jar is a rigid, cylindrical or slightly conical container, typically made of glass, ceramic, or plastic, with a wide mouth or opening that can be closed with a lid, screw cap, lug cap, cork stopper, roll-on cap, crimp-on cap, press-on c ...

, LHA/LZH, LZMA, MSLZ,

Office Open XML Office Open XML (also informally known as OOXML) is a zipped, XML-based file format developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents. Ecma International standardized the initial versi ...

, onepkg,

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimension ...

, smzip,

SWF SWF ( ) is an Adobe Flash file format used for multimedia, vector graphics and ActionScript.Open Screen Pr ...

XAR Xar may refer to: * Xar (graphics), a file format used with vector graphics * XAR, a file archiver and its associated file format * Michael Portnoy, who uses the stage name XAR * The ICAO The International Civil Aviation Organization (ICAO ...

, and Z archives and

cramfs The compressed ROM/RAM file system (or cramfs) is a free (GPL'ed) read-only Linux file system designed for simplicity and space-efficiency. It is mainly used in embedded and small-footprint systems. Unlike a compressed image of a conventional f ...

DMG DMG may refer to: Organizations Entertainment * Dames Making Games, a Canadian non-profit organization that encourages the participation of women, non-binary, femme and queer people in the creation of video games * Davidson Media Group, an American ...

FAT In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple es ...

HFS HFS may refer to: Computing * Hardware functionality scan, a security mechanism used in Microsoft Windows operating systems * Hierarchical File System, a file system used by Apple Macintosh computers * Hierarchical File System (IBM MVS), used MV ...

ISO ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Is ...

MBR MBR may refer to: Computing * Master boot record, the first sector of a partitioned data storage device, used for booting * Memory buffer register * Minimum bounding rectangle * Minimum bit rate Publications * ''The Malaysia Book of Records'' * ...

NTFS New Technology File System (NTFS) is a proprietary journaling file system developed by Microsoft. Starting with Windows NT 3.1, it is the default file system of the Windows NT family. It superseded File Allocation Table (FAT) as the preferred f ...

SquashFS Squashfs is a compressed read-only file system for Linux. Squashfs compresses files, inodes and directories, and supports block sizes from 4 KiB up to 1 MiB for greater compression. Several compression algorithms are supported. Squashfs is als ...

, UDF, and VHD

disk image A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is usu ...

s. 7-Zip supports the ZIPX format for unpacking only. It has had this support since at least version 9.20, which was released in late 2010. 7-Zip can open some MSI files, allowing access to the meta-files within along with the main contents. Some Microsoft CAB (

LZX LZX is an LZ77 family compression algorithm, a slightly improved version of DEFLATE. imlib: the open source Windows Imaging (WIM) library - Compression algorit hmhttps://wimlib.net/compression.html/ref> It is also the name of a file archiver wit ...

compression) and NSIS (LZMA) installer formats can be opened. Similarly, some Microsoft executable programs (. EXEs) that are self-extracting archives or otherwise contain archived content (e.g., some setup files) may be opened as archives. When compressing ZIP or gzip files, 7-Zip uses its own DEFLATE encoder, which may achieve higher compression, but at lower speed, than the more common

zlib zlib ( or "zeta-lib", ) is a software library used for data compression. zlib was written by Jean-loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. zlib is also a ...

DEFLATE implementation. The 7-Zip deflate encoder implementation is available separately as part of the AdvanceCOMP suite of tools. The decompression engine for

archives was developed using freely available source code of the unRAR program, which has a licensing restriction against creation of a RAR compressor. 7-Zip v15.06 and later support extraction of files in the RAR5 format. Some backup systems use formats supported by archiving programs such as 7-Zip; e.g., some Android backups are in tar format, and can be extracted by archivers such as 7-Zip. 7-Zip ZS, a port of 7-Zip FM with Zstandard .zst (and other formats) support, is developed by Tino Reichardt. Modern7z, a Zstandard .zst (and other formats) plugin for 7-Zip FM, is developed by Denis Anisimov (TC4shell).

File manager

7-Zip comes with a file manager along with the standard archiver tools. The file manager has a toolbar with options to create an archive, extract an archive, test an archive to detect errors, copy, move, and delete files, and open a file properties menu exclusive to 7-Zip. The file manager, by default, displays hidden files because it does not follow

Windows Explorer File Explorer, previously known as Windows Explorer, is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface for accessing the file ...

's policies. The tabs show name, modification time, original and compressed sizes, attributes, and comments (

4DOS 4DOS is a command-line interpreter by JP Software, designed to replace the default command interpreter COMMAND.COM in Microsoft DOS and Windows. It was written by Rex C. Conn and Tom Rawson and first released in 1989. Compared to the default ...

descript.ion format). When going up one directory on the root, all drives, removable or internal appear. Going up again shows a list with four options: * Computer: loads the drives list * Documents: loads user's documents, usually at %UserProfile%\My Documents * Network: loads a list of all network clients connected * \\.: Same as "Computer" except loads the drives in low-level

access. This results in critical drive files and deleted files still existing on the drive to appear. (NOTE: As of November 2020, access to the active partition in low-level mode is not allowed for currently unknown reasons.)

Features

7-Zip supports: * 32 and 64-bit architecture support * File Manager * Encryption via the 256-bit

AES AES may refer to: Businesses and organizations Companies * AES Corporation, an American electricity company * AES Data, former owner of Daisy Systems Holland * AES Eletropaulo, a former Brazilian electricity company * AES Andes, formerly AES Gener ...

cipher, which can be enabled for both files and the 7z hierarchy. When the hierarchy is encrypted, users are required to supply a

password A password, sometimes called a passcode (for example in Apple devices), is secret data, typically a string of characters, usually used to confirm a user's identity. Traditionally, passwords were expected to be memorized, but the large number of ...

to see the filenames contained within the archive. WinZip-developed Zip file AES encryption standard is also available in 7-Zip to encrypt ZIP archives with AES 256-bit, but it does not offer filename encryption as in 7z archives. * Volumes of dynamically variable sizes, allowing use for backups on removable media such as writable CDs and DVDs * Usability as a basic

orthodox file manager A file manager or file browser is a computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, opening (e.g. viewing, playing, editing or print ...

when used in dual panel mode * Multiple-core CPU threading * Opening EXE files as archives, allowing the decompression of data from inside many "Setup" or "Installer" or "Extract" type programs without having to launch them * Unpacking archives with corrupted filenames, renaming the files as required * Create self-extracting single-volume archives * Command-line interface * Graphical user interface. The Windows version comes with its own GUI; however, ''p7zip'' uses the GUI of the Unix/Linux Archive Manager. * Calculating

checksums A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data ...

in the formats CRC-32, CRC-64, SHA-1, or SHA-256 for files on disk, available either via command line or Explorer's context menu * Available in 87 languages * Ability to optionally record creation dates (tc) and last access dates (ta) in archives (in addition to modification dates).

Variants

Two

command-line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive command (computing), commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invokin ...

versions are provided: 7z.exe, using external libraries; and a standalone executable 7za.exe, containing built-in modules, but with compression/decompression support limited to 7z,

, bzip2, Z and

formats. A 64-bit version is available, with support for large memory maps, leading to faster compression. All versions support multi-threading. The 7za.exe version of 7-Zip is available for

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating systems (including

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

, and

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

FreeDOS FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems. FreeDOS ca ...

OpenVMS OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Ope ...

AmigaOS 4 AmigaOS 4 (abbreviated as OS4 or AOS4) is a line of Amiga operating systems which runs on PowerPC microprocessors. It is mainly based on AmigaOS 3.1 source code developed by Commodore International, Commodore, and partially on version 3.9 develop ...

, and

MorphOS MorphOS is an AmigaOS-like computer operating system (OS). It is a mixed proprietary and open source OS produced for the Pegasos PowerPC (PPC) processor based computer, PowerUP accelerator equipped Amiga computers, and a series of Freescale devel ...

under the ''p7zip'' project.

Software development kit

7-Zip has a LZMA SDK which was originally

dual-licensed Multi-licensing is the practice of distributing software under two or more different sets of terms and conditions. This may mean multiple different software licenses or sets of licenses. Prefixes may be used to indicate the number of licenses ...

under both the

GNU LGPL The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

and

Common Public License In computing, the Common Public License (CPL) is a free software / open-source software license published by IBM. The Free Software Foundation and Open Source Initiative have approved the license terms of the CPL. Definition The CPL has the ...

, with an additional special exception for linked binaries. On 2 December 2008, the SDK was placed by Igor Pavlov in the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

Security

On older versions, self-extracting archives were vulnerable to

arbitrary code execution In computer security, arbitrary code execution (ACE) is an attacker's ability to run any commands or code of the attacker's choice on a target machine or in a target process. An arbitrary code execution vulnerability is a security flaw in softwar ...

through

DLL hijacking Dynamic-link library (DLL) is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems. These libraries usually have the file extension DLL, OCX (for libraries containing ActiveX controls), or ...

: they load and run a DLL named UXTheme.dll, if it is in the same folder as the executable file. 7-Zip 16.03 Release notes say that the installer and SFX modules have added protection against DLL preloading attack. Versions of 7-Zip prior to 18.05 contain an

vulnerability in the module for extracting files from RAR archives (), a vulnerability that was fixed on 30 April 2018.

Reception and usage

Snapfiles.com in 2012 rated 7-Zip 4.5 stars out of 5, noting, " tsinterface and additional features are fairly basic, but the compression ratio is outstanding". On

TechRepublic TechRepublic is an online trade publication and social community for IT professionals, providing advice on best practices and tools for the needs of IT decision-makers. It was founded in 1997 in Louisville, Kentucky, by Tom Cottingham and Kim S ...

in 2009, Justin James found the detailed settings for Windows File Manager integration were "appreciated" and called the compression-decompression benchmark utility "neat". And though the archive dialog has settings that "will confound most users", he concluded: "7-Zip fits a nice niche in between the built-in Windows capabilities and the features of the paid products, and it is able to handle a large variety of file formats in the process." Between 2002 and 2016, 7-Zip was downloaded 410 million times from

SourceForge SourceForge is a web service that offers software consumers a centralized online location to control and manage open-source software projects and research business software. It provides source code repository hosting, bug tracking, mirrori ...

alone. The software has received awards, In 2007, SourceForge granted it community choice awards for "Technical Design" and for "Best Project". In 2013,

Tom's Hardware ''Tom's Hardware'' is an online publication owned by Future plc and focused on technology. It was founded in 1996 by Thomas Pabst. It provides articles, news, price comparisons, videos and reviews on computer hardware and high technology. The si ...

conducted a compression speed test comparing 7-ZIP, MagicRAR,

WinRAR WinRAR is a trialware file archiver utility for Windows, developed by Eugene Roshal of win.rar GmbH. It can create and view archives in RAR or ZIP file formats, and unpack numerous archive file formats. To enable the user to test the integrity of ...

, WinZip; they concluded that 7-ZIP beat out all the others with regards to compression speed, ratio, and size and awarded the software the 2013 Tom's Hardware Elite award.

References

External links

* *
7-Zip Portable
at

PortableApps.com PortableApps.com is a website offering free applications for Windows that have been specially packaged for portability. These portable applications are intended to be used from removable media such as USB flash drives. User data is stored in a s ...

{{FOSS 1999 software Cross-platform free software Disk image extractors File archivers Free data compression software Free file managers Free multilingual software Free software programmed in C Free software programmed in C++ Portable software Software using the LGPL license Windows compression software

Archive formats

7z

Others

File manager

Features

Variants

Software development kit

Security

Reception and usage

See also

References

External links